FWIW, since you mentioned the Edirol FA101 in your initial post: I've been using one for well over a decade, and it's worked beautifully on Linux the whole time.
I was not happy about retiring it, but my Firewire-equipped workstation packed it in, and I can't justify buying another just to get that interface. Not yet, anyway.

To replace it in the medium term, I bought a Mackie Producer 2x2, partly because they make a point of explicitly supporting Linux. For €109, I'm impressed - that thing's good! For as long as you can get by on 2 ins, 2 outs and MIDI in/out, it's worth seriously considering.

Jamesf wrote:
To replace it in the medium term, I bought a Mackie Producer 2x2, partly because they make a point of explicitly supporting Linux. For €109, I'm impressed - that thing's good! For as long as you can get by on 2 ins, 2 outs and MIDI in/out, it's worth seriously considering.

Waveform OEM is a multi award-winning workstation, featuring powerful and creative tools to inspire the modern musician. Unlike typical ‘Lite’ versions, it does not impose any restrictions – you get unlimited track count, powerful features, compatibility with all popular plugins and efficient performance on Mac®, Windows®, and Linux® operating systems.

Jamesf wrote:
To replace it in the medium term, I bought a Mackie Producer 2x2, partly because they make a point of explicitly supporting Linux. For €109, I'm impressed - that thing's good! For as long as you can get by on 2 ins, 2 outs and MIDI in/out, it's worth seriously considering.

I've used it to capture the MIDI output from a Beatbuddy drum-machine/pedal, so I can confirm that that side of things works neatly as well. At least, it does with Jack and Ardour.

CrocoDuck wrote:I was reading the page and the manual, but I did not found any statement of Linux hardware compatibility, just this about related software
...
To your knowledge, is the Linux hardware compatibility stated somewhere?

Looking back through it, maybe it isn't :scratches head:

Looks like I leapt to conclusions based on the mention of Linux compatibility for the software bundled with it, and the explicit mention of LinuxVST compatiblity in the manual. It seemed unlikely that they'd associate that with a device that isn't compatible, though it's true that it wouldn't be the first time a vendor made that mistake.

Well, in practice it's almost disconcertingly plug-and-play class-compliant, so at least I leapt to a correct conclusion.